Apparatus for distilling petroleum and the like



April 2, w35- w. M. FRASER APPARATUS FOR DISTILLING PETROLEUM AND THE LIKE v Filed April 10, 1954 Patented Apr. 21, 1936 UNITED STATES PPARATUS FR DISTILLING PETROLEUM AND THE LIKE William M. Fraser, Bristow, Okla.

Application April li), 1934, Serial Nc. 719,933

3 Claims.

My invention relates generally to an apparatus for separating the lighter fractions from petroleum and the like without subjecting the lighter fractions to excessive heat, and to an apparatus suitable for carrying out the process, and an important object of the invention is to provide an apparatus enabling removing the lighter fractions from the heating coil or other part of the still as and whenthe lighter fractions vaporize.

Another important object of my invention is to provide a process and an apparatus enabling a considerable saving in fuel, Whether the distillation be in a closed still or in an open still.

Another important object of the invention is to provide an apparatus enabling avoiding eX- cessive cracking and gas formation, and to obtain the lighter fractions in a condition in which they do not have as wide a boiling range, and prevent the formation of coke.

Other objects and advantages of my invention will be apparent from a reading of the following description in connection with the drawing, wherein for purposes of illustration I have shown one embodiment of an apparatus suitable for the carrying out of the process of my invention.

In the drawing:-

The single View is a longitudinal vertical sectional view through a trap in accordance with my invention for incorporation in a conventional petroleum distilling apparatus.

Operation of tube or pipe stills for the fractional distillation of petroleum and other similar crude liquids provides a continuous operation in the sense that the crude oil or the like is pumped continuously through the tubes, being at the same time heated to the temperature necessary to vaporize the highest boiling point fractions. Substantially the same procedure is followed whether the oil is subjected to pressure as in a process of cracking or whether the process is one of atmospheric distillation in which the pressure used is merely that necessary to overcome the frictional resistance in the heating coil. In these presently used processes the fractions of lowest boiling point are heated to the same temperature as the fractions of highest boiling point, so that the fractions of lowest boiling point are heated to a much greater temperature than is required for their vaporization. These processes are the most efficient commercially practical processes now known, but in them inhere excessive use of fuel, excessive cracking and gas formation, the lighter oils obtained have an objectionably wide boiling range, and excessive coking takes place.

By my invention I am enabled to trap and recover the lighter fractions in vapor form, and without any stoppage of the progress of the oil through the still, the trapping and recovery of the vaporized lighter fractions taking place as (Cl. ISG-4.10)

the lighter fractions are vaporized, so that the lighter fractions in their vaporized state are not required to pass to regions of highest temperature wherein they are injured in the present processes. Another advantage of my invention is that the common receiving tank, usually called the reaction chamber, for a series of distilling units may be eliminated in the operation of cracking or in the use of atmospheric tube stills, and the finished residuum led directly to storage from the coil. While the elimination of the reaction chamber and the leading of the residuum directly to storage is not an essential step in my process, it may be included if found desirable according to the results sought, which will usually be iniiuenced by the need for economy or by the construction of the tube still being used. It is to be observed that my process enables the einnination to be made where other processes require the presence of the reaction chamber.

The trapping is accomplished by arranging for a reduction in pressure in the pipe of the still which enables the vapor to escape from the oil, the oil continuing on without interruption to the regions of higher temperature. It is to be observed that under the conditions contemplated the vapors are initially non-existent, the lighter fractions being maintained in a liquid state by the maintenance of the pressure. The reduction in pressure at the temperature and at the locality selected causes the lighter fractions to vaporizc at a comparatively low temperature and pressure and escape from the oil. Suitable means for collecting the escaping vapors is provided. Should it be desired to further crack the segregated lighter fractions obtained by collection of the escaping vapors, the segregated lighter fractions may be passed directly through another cracking coil for further cracking or reforming.

The establishment of conditions for escape of the lighter fraction vapors from the oil in the still may be provided at different points in the still, so that each point is localized.

A suitable apparatus for interpolation in a still of the character described is shown in the drawing, wherein the numerals 5 and 6 refer respectively to separated points in the pipe of a still. On one side of the pipe there is provided a relatively large casing 'l forming a chamber for reception of the oil vapors, and a relatively smaller enlargement 8 of the tube on the down stream side of the chamber 1 serves as a secondary chamber. The outer end of the secondary chamber is connected by a small pipe 9 controlled by a valve I0 with one side of the chamber 'I as indicated'at II. The outer end of the chamber 'l has leading therefrom a small pipe i 2 controlled by the valve I`3. The arrows indicate the direction of travel of the oil through the pipe of the still.

Inverted cones I4, l5 operating on a principle similar to that found in the action of a Venturi tube are utilized to cause the localized reduction in pressure in the still pipe. The cone I4 has its base at the point I6 which is upstream from the side of the chamber I and has its open reduced end Il located at about the center of the chamber l. The cone I5 is inverted with respect to the cone I4 and has its small end I8 arranged longitudinally spaced from the small end I1 of the cone I4 and approximately at the center of the chamber 'L The small end I8 of the cone I5 is larger than the small end I1 of the cone I4 so that the edges of the end I8 are concentrically spaced radially outwardly from the end I'I of the cone I4, so that the cone I4 delivers the oil in a converged stream into the small end I8 of the cone I5. It is obvious that the oil entering the large end of the cone I4 will be throttled as it moves toward the small end I'I of the cone I4 and that this condition results in a reduction in pressure within the chamber 'l which permits the oil at the temperature at which it reaches this place to give oil such vapors as compose the lighter fractions. When the oil leaving the small end II of the con-e I4 reaches and enters the small end I8 of the cone I5 it then resumes gradually its normal gait as it moves toward the larger cross section of the downstream end of the cone it and into the downstream portion 5 of the still tube.

Assuming for purposes of illustration that the heated oil is ilowing in a cracking tube 5 of the still coil at a pressure of 400 pounds as it reaches the cone I4, the orices of the cones I4 and I5 may be so arranged that upon reaching the small end of the cone I5 the oil pressure will have been reduced to 30G pounds. The result is a reduction of the pressure within the chamber 1. It is possible to arrange the cones so that there will be produced in the chamber 'l almost a complete vacuum. Ordinarily a reduction in pressure ci i0 pounds is suitable for separating the lighter fractions by causing their vaporization at the point indicated.

Assisting means over and above the cones and the chamber 'I are required to make the process practical, and suitable assisting means is cornprised by the smaller chamber 8. Owing to the speed at which the oil is traveling and the pressure thereof, there being in the example given, a reduction of pounds of pressure, vapors will pass from the point between the cones, through the cone I5 and collect in the chamber 8, from which they are passed into the chamber 'I through the communicating pipe 9.

When a small amount of the oil passes along with the vapors into the chamber 1 and into the chamber 8, such oil will be taken into the cone or nozzle I5 by the syphoning action resulting from the passage of the oil in the downstream direction across the openings of the described parts. The collected vapors in the chamber I will be led off through the pipe i2. If desired the pipe I2 may lead directly to a second cracking still for further cracking or reforming.

If desired orice plates may be substituted for the upstream cone I4 for reducing the pressure, but I prefer the hollow cones described above as being more positive and convenient in action.

The vapor separating device described above may be inserted easily and economically in any of the conventional tube still heating systems by attaching different units on the outside of the ring chamber where return bends are installed. The device should be constructed of steel with flange connections so that the parts may be removed at will when the still is to be taken down for cleaning or repair. The device of the invention may also serve conveniently as a means for introducing other oils into the cracking tubes at desired points. Such additive oils and other materials can be added by feeding'the same into the chamber 1 under reduced pressure, whence it is syphoned into the heating coils through the cone or orice I5.

Although I have shown only one. of the devices of the invention installed in the tube of a still, it is obvious that the description of this device will suiiice for the description of a plurality of such devices which will usually be used.

Although I have shown and described herein preferred embodiments of my invention, it is to be denitely understood that I do not desire to limit the application of the invention thereto, and any change or changes may be made in material and structure and arrangement of parts, and in the sequence and duration of steps and operations, within the spirit of the invention and the scope of the subjoined claims.

What is claimed is:-

l. A selective vapor trapping device of the character described for interpolation in a heated oil pipe of a continuously operating still, said device consisting of means located within the tube and arranged to locally reduce the pressure within said tube without interrupting the flow of the oil therethrough, receptacle means in communication with the inst-mentioned means for receiving the vapors of lighter fractions, and discharge means for said vapors -connected to said second means; and a chamber beyond the lirst-mentioned means and in communication with said tube for receiving and collecting vapors carried beyond said nrst means, and a valved conduit connecting said chamber with said receptacle.

2. A device of the character described for interpolation in the tube of a still through which heated oil is moving under pressure, said device consisting of a member formed with a pair of opposed orifices causing a reduction of pressure within the tube Without interrupting the flow of the oil through the tube, a vapor collecting chamber in vapor receiving relation to the space between the said orifices, means on said chamber for leading the collected vapors away, a second vapor collectlng chamber located beyond the rst inentioned chamber and communicating with said tube and with said rst mentioned chamber whereby said rst chamber has a suction on the contents of the second chamber.

3. A device of the character described for interpolation in the tube of a still through which heated oil is moving under pressure, said device consisting of a member containing a pair of opposed orices causing a reduction of pressure within the tube without interrupting the flow of the oil through the tube, a vapor collecting chamber in communication with the space between the said orices, means on said chamber for leading 3 collected vapors away, and a vapor collecting chamber located downstream from said orifices and said rst chamber for receiving vapors carried beyond said orifices, the last named chamber being communicable. with the first chamber, the means rendering the said chambers communicable being so arranged that said first chamber has a suction upon the contents of last named chamber.

WILLIAM M. FRASER. 

